In order to perform asset management, inventory taking is carried out at business enterprises, etc., on a regular basis. For example, in an inventory taking using bar codes, locations of assets are checked by scanning recording media, such as bar codes, etc., attached on managed assets by a bar code reader. It is preferable for an operator who takes an inventory to grasp where the managed assets are located. Accordingly, a manager creates a floor map of a building, and there arises marking work of places where managed assets are located. However, if the number of managed assets becomes large, a burden on the manager increases, and recording of position data becomes difficult. In order to handle this problem, there is a method of including character information indicating a position by a text, such as “disposed at a south side of the building on the 10-th floor”, for example, in information on assets of an asset management apparatus.
In this regard, the following technique has been proposed on creation of a map. For example, a technique has been proposed in which a movement locus from leaving an existing road on map data to returning is memorized as an undetermined route, and if two memorized undetermined routes has a high correlation coefficient, the undetermined route is stored in map data as a new road. Also, a technique has been proposed in which an estimated position of a mobile robot in an estimated coordinate system is calculated from a movement direction and a movement distance, a position of a known reference object is measured to obtain the position of the reference object in the estimated coordinate system, and the movement direction and position in an absolute coordinate system is calibrated from the position in the estimated coordinate system.
However, there is a problem in that when positions of managed assets are controlled by texts in the same manner as in related arts, it is difficult to grasp the positions of the managed assets.
In this regard, in the technique of storing a data item of a new road in a map, if a road uncharted on the map is not passed through two times, that road is not registered in the map as a new road. Accordingly, in the case of inventory taking in which various movement paths are drawn on a floor, it is difficult to create a floor map from a movement locus. Also, in the technique of calibrating a movement direction and position in an absolute coordinate system, it is a prerequisite that a position of a known reference object in absolute coordinates is already known. In the case where absolute coordinates are unknown, it becomes difficult to calibrate a movement direction and position in the absolute coordinate system.